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DETERMINANTS OF NUTRITIONAL REQUIREMENTS OF SPINAL CORD INJURED ATHLETES

Ingrid Perols

A thesis submitted in partial fulfilment of the requirements for the degree of

Master of Science 1n

Nutritional Science

Massey University, Albany , New Zealand.

2000

ERRATUM

Throughout this thesis, and particularly in the abstract, results and discussion

sections, where reference is made to the dietary intake data collected in this study it

should be acknowledged that due to the lack of validity and reliability of the method

of dietary data collection used (self-reported intakes in the form of a food diary) these

are reported intakes and cannot be considered as actual intakes.

In the "Abstract", line 28 the unit for energy intake should be stated as kilojoules and

not as incorrectly stated in kilocalories. The sentence should read: "The mean

reported energy intake was 8678 ± 2411 kJ per day ... ".

Abstract

Disability sport is attracting more participants and is becoming increasingly

competitive. Athletes with spinal cord injury (SCI) resulting in quadriplegia face

a number of physiological limitations such as reduction in lean body mass,

increased fat mass and altered physiological responses to exercise, as a

direct consequence of their injury. Long-term health consequences of spinal

cord inju ry such as cardiovascular disease, type 2 diabetes and osteoporosis

occur earlier than in the able-bodied population.

The aims of this study was to investigate the nutritional status and some of the

physiological characteristics likely to impact on the nutritional requirements of

SCI athletes.

Sixteen wheelchair rugby players currently playing for a regional team in the

1999 NZ National Wheelchair Rugby Tournament were recruited . Subjects

completed a brief demographic questionnaire to provide information about

their injury , and 7-day food diary for assessment of dietary intake during the

competition season. Body composition and bone mineral density were

assessed by dual-energy x-ray absorptiometry (DEXA) and an arm-cranking

test was performed in a laboratory situation to assess heart rate response and

oxygen uptake during exercise. Finally , monitoring of heart rate in a game

situation was performed on three subjects.

Body composition data showed that subjects had a body mass index (BMI)

(26.4 g/cm2) similar to that of the general New Zealand population and to

paraplegic subjects in New Zealand . However, lean body mass was low

(60.1 % of total body mass) and body fat was re latively high (34.9% of body

mass) in comparison to both the general population and to other athletes.

Mean whole body bone mineral density for the group was within the normal

range however, five subjects were classified as having osteopenia and of

those , two were classified as having osteoporosis . The mean energy intake

was 8678 ± 2411 kcal per day, significantly below that of NZ males in the

same age groups [1 ]. The contribution from carbohydrate , protein and fat to

total energy intake was virtually identical to that of the general NZ population

[1] . Many of the subjects did not meet the Recommended Dietary Intake (ROI)

for a number of micronutrients .

Heart rate (HR) response and oxygen uptake (V02) was similar to that found

in other studies [2] . Interestingly , the relationship between HR and V02

showed a linear increase during the graded exercise test resulting in a

coefficient of determination above 0.923 for all subjects.

Heart rate profiles were recorded for three subjects in a game situation and

energy expenditure was calculated from V02 data from the laboratory

exercise test. The three subjects had a calculated energy expenditure ranging

from 3.7-7 .2 kcal/minute of exercise.

It was concluded that BMI may not be an accurate method to assess obesity

in quadriplegic subjects and body composition assessment by DEXA provides

a more accurate method for determining changes in body composition and

bone mineral density over time. It was further concluded that many subjects

had low energy intakes resulting in suboptimal intakes of macronutrients.

Many subjects would benefit from dietary advice with a view to improve

general health and exercise performance. Heart rate monitoring for the

II

purpose of estimating energy expenditure should be investigated further in this

population as should other factors likely to impact on both general health and

exercise performance.

111

Acknowledgements

I would like to thank the following people for the valuable assistance they have

provided during the completion of this research project:

Dr Clare Wall

Dr Alan Doube

Carl Paton

Lecturer, Institute for Food , Nutrition and Human Health ,

Massey Universtiy

Rheumatologist , Waikato Bone Density Service,

Hamilton

Lecturer, Exercise Physiology, Waikato Polytechnic

I would also like to thank the New Zealand Dietetic Association and the late

Neige Todhunter, and Sports Science New Zealand for providing funding for

this research project.

IV

Table of Contents

1 Introduction 1

2 Literature Review 4

2.1 Wheelchair Rugby 4

2.1.1 The History of Wheelchair Rugby in New Zealand 4

2.1.2 The rules of the Game 4

2.2 Spinal Cord Injury 5

2.2 .1 The Spinal Cord 6

2.3 Life and Health Expectancy After Spinal Cord Injury 8

2.4 Obesity, Cardiovascular Disease and Type 2 Diabetes 10

2.5 Osteoporosis 13

2.6 Physiological Consequences of Spinal Cord Injury 19

2.6.1 Cardiovascula r System 20

2.6.2 Exercise Responses 21

2.6.3 Thermoregulation 25

2.7 Body Composition 26

2.8 Energy Expenditure During Rest and Exercise 31

2.8.1. Estimating Energy Expenditure by the Use

of Heart Rate Monitoring 33

2.9 Exercise Testing 34

2 .10 Current Nutrition Recommendations for Wheelchair Sport 36

2.10.1 Dietary Intake of Sp inal Cord Injured Individuals 38

2.11 Assessment of Dietary Intake 39

v

3 Aims of the Study 41

4 Methodology 42

4.1 Dietary Assessment 42

4.2 Body Composition and Bone Mineral Density 43

4.3 Exercise Test 44

4.4 Heart Rate Monitoring in a Game Situation 46

5 Results 48

5.1 Demograph ic Data and Phys ical Characteristics 48

5.2 Body Composition and Bone Density 49

5.3 Dietary Intake 50

5. 3. 1 Energy and Macronutrient Intake 50

5.3 .2. Micronutrient Intake 54

5.4 Exercise Test 55

5.5 Heart Rate Monitoring in a Game Situation 56

6 Discussion 58

6.1 Anthropometric Characteristics and Body Composition 59

6.2 Bone Mineral Density 62

6.3 Dietary Assessment 66

6.4 Exercise Testing 74

6.5 Heart Rate Monitoring in a Game Situation 76

6.6 Recommendations 78

6.7 Limitations 79

7 Conclusions 81

References 85

VI

Appendices

1 Invitation to Participate in a Research Study

2 Consent Form

3 Demographic Questionnaire

4 Food Diary

5 Technical Description of the DEXA Technique

6 Individual Bone Mineral Data

7 Sample DEXA Scan

SA Individual Subjects' Dietary Intake of Energy, Macronutrients and

Alcohol (graph)

8 B Individual Subjects ' Dietary Intake of Energy, Macronutrients and

Alcohol

9 Individual Heart Rate/Oxygen Uptake Graphs from the

Exercise Test

10 Sample of a Heart Rate Recording from a Wheelchair Rugby

Game

96

97

98

99

100

101

102

103

104

105

106

VII

List of Tables

5.1 Demographic Data for Each Subject 48

5.2 Anthropometric Data for the Study Group 49

5.3 Data for Bone Mineral Density and t-scores for the Study Group 49

5.4 Daily Intake of Energy, Macronutrients, Alcohol and Fibre 51

5.5 Contribution of Different Fatty Acids to Total Energy Intake 53

5.6 Micronutrient Intake in Comparison to the Recommended

Dietary Intake for New Zealanders 54

5.7 Oxygen Uptake, Heart Rate and Power Output for the Group 56

VII I

List of figures

2.1 The Spinal Cord and the Spinal Nerves

4 .1 Set-up for the Exercise Test

5.1 Contribution of Carbohydrate, Protein , Fat and Alcohol to

7

45

Total Energy Intake 51

5.2 Heart Rate and Oxygen Consumption Data for Two Subjects 56

IX